Prediction of peak oxygen consumption by incremental 6minutes walking test in patients with Ischemic heart disease after cardiac rehabilitation

Introduction For ischemic heart disease patients (IHD), Cardiac rehabilitation (CR) helps to recover the functional capacity. Stress test with oxygen peak consumption (VO2 max at peak) at CR discharge is a key point to determine physical capacity. There was no regression equation available to predict oxygen peak consumption (VO2 max at peak) at discharge. The aim of our study was to develop an equation to predict VO2 peak values at discharge. Materials and methods It is a retrospective study including 68 patients with IHD admitted for CR. They all had of 6 minutes walking Test before and after CR and also underwent a stress test with Ergospirometry at the beginning of CR. The study end point was to develop an equation to predict VO2 max at peak at their discharge using only the results of the two six minutes walking tests (entry and at discharge) and the VO2max at peak exercice at the beginning of their Cardiac rehab. Results The average age of patients was 52,14 ± 10,1 years with male predominance (80%), they had more than three cardiovascular risk factors dominated by smoking and hypertension. After 20 sessions of CR, they significantly increase 6 minutes walking test (from 488,18 ± 101,29 m to 560,61 ± 100,20 m) and their VO2max(from 20,74 ± 5,41 ml/kg/min to 23,52 ± 6,46 ml/kg/min). Using linear regression analysis, we developed an equation to calculate the Final VO2 max at peak (predicted) = 1,167 + (0,95x initial VO2peak) + (0,002x initial 6MWT) + (0,003x final 6MWT). There was no statistically significant difference between the VO2 peak measured directly and the predicted one with our equation. Conclusion This study showed that cardiac rehabilitation, can avoid a final stress test with VO2max using our predicted equation. This new method to predict the VO2max at peak at discharge from CR is easy to use and can be cost effective saving a whole test with ergospirometry at discharge. This study needs to be confirmed by a larger number of patients included.